Supermarket giant Coles has agreed to correct claims it made in a social media campaign about its store brand milk.

The Australian Competition and Consumer Commission (ACCC) investigated the Our Coles Brand Milk Story campaign after it received complaints from dairy farmer organisations.

The consumer watchdog says Coles published the campaign's video and cartoon during a time of intense public debate about the impact of $1 milk on Australian dairy farmers.

The price cut was announced in January 2011 and played out as a major part of the supermarket price wars.

As part of its decision to heavily discount milk, Coles ran its social media campaign from February to May last year on YouTube.

The campaign also featured on the Coles website and its Facebook page, and was promoted on Twitter.

"Coles represented in a video and cartoon on social media that the farm gate milk price increased from 86 cents per two-litre bottle of Coles-brand milk in 2010-11 to around 90 cents in 2011-12, when in fact this was an estimate," ACCC chairman Rod Sims said in a statement.

Mr Sims says the commission is keen to ensure accuracy in advertising is maintained regardless of the medium.

"The ACCC is concerned to ensure that companies are applying the same degree of Australian Consumer Law compliance to representations made in social media versus other forms of advertising," he added.

"For this reason, the ACCC considered it was important that Coles used social media to correct any misleading impressions formed by viewers.

"The ACCC was concerned that Coles presented estimates and opinions as facts and that a number of representations made in the video and cartoon could not be substantiated by Coles."

The ACCC says Coles has admitted that its making of these representations would be likely to have contravened section 18 of the Australian Consumer Law, which prohibits misleading or deceptive conduct.

It says Coles has worked with the ACCC to resolve these concerns, and will publish corrective advertisements on the same online platforms that the original representations were published.

The undertaking also requires Coles to not make misleading or deceptive representations in relation to the impact of reductions in the retail price for Coles brand milk on the farm gate milk prices, Coles' or processor margins on Coles-brand milk, and/or Australian milk production generally for a period of three years.

The supermarket giant has also been directed to review its Australian Consumer Law compliance program.

Coles says it believes the key message in the campaign was correct, but says it accepts that some of the supporting information was based on estimates which were later updated.

Last year, Australian Dairy Farmers said the "lack of competition within the supermarket industry, and Coles' subsequent purchasing power, means $1 milk continues to hurt farmer and processor profits."

"The current price paid to both farmers and processors in today's market is unsustainable.

"In the drinking milk states of Queensland, New South Wales and Western Australia, for example, the milk price war has seen some farmers' already poor profit margins crunched by a further 3 to 4 cents per litre. Milk processors face a similar dilemma."